Safety signal system.



" e. P. THURBER.

SAFETY SIGNAL SYSTEM.

APPLICATION FILED NOV. I. I9II.

5 SNEETS SHEETL Patented m 3,1911

Attorneys G. P. THURBER.

SAFETY SIGNAL SYSTEM.

APPLICATION FILED NOV- l. I911 Patented July 1917.- l

5 SHEETS--SHEET 3.

wag Q Witnesses i ventol by v ,7? ,l zr 4 l w I Maw Attorneys.

G P. THURBER.

SAFETY SUN/XL SYSTEM. APPUCAHON mu) NM. 1. HJH.

1 Patented July 3, 19171 I 5 SHEETS SHUT 4.

W itnesses Attorneym G. P. THURBER.

SAFETY SIGNAL SYSTEM. APPLICATION FILED NOV. i, I911- 1,'232,442Q Patented J 1113* 3, 1917?.

SSHEETS SHEET 5.

Attorneys UNITED STATES PATENT OFFICE.

P. THURBER, OE PITTSBURGH, PENNSYLVANIA, ASSIGNOR, BY MESNE ASSIGN- MENTS, TO AUTOMATIC TRAIN CONTROL 8a SIGNAL COMPANY, OF PITTSBURGH, PENNSYLVANIA, A CORPORATION OF DELAWARE.

SAFETY SIGNAL SYSTEM.

mesa 142.

Specification. of Letters Patent.

Application filed November 1, 1911. Serial No. 658,033.

To all whom it may concern:

Be it known that I, GUY P. T -rn'nnnn, a citizen of the United States, residing at Pittsburgh, in 'the county of Allegheny and State of Pennsylvania, have invented a new and useful Safety Signal System, of which the following is a specification.

The present invention relates to improye' ments in safety signal systems, and more particularly-is a safety signal system espe ,cially adapted for use in connection with l electric traction or interurban railroads proi Tst opped or notified to avoid accidents, and

'vid'ed with a single track intended for trafiic in bothdirections, this particular system referrin'g to the track or rail connections, and designed for use in connection with the cab or motor car mechanisms, as set forth in applicantis case filed April 16, 1911, Serial .Inthis particular signal system, train controlling points are located along the traclt, and areeach'pr'ovided with a loop circult controlled by a circuit breaker frorn a distant point, and when opened forms a means of automatically cutting ofi the power and setting the brakes upon the car or train, as well as giving signals to the car or train which passes over the insulated joints at either end of the blocks or signal points.

To produce a signal system adapted for safety upon this class of railroads, it is essential that when acar or train enters a block, that anapproaching car or train in either direction, that is in front or in rear of the car or train Within the block, must be to this'end, this invention has been devised.

With the foregoing and other objects in view which will appear asthedescription roceeds, the invention resides the comination and arrangement of parts and in the details of. construction hereinafter described and claimed, it being understood that changes in' t he precise embodiment of ,the invention herein disclosed can be made within the scope of What is claimed without I de arting frointhespirit of the invention.

Blithe drawings 2-.-

1. 1- .Figure 1 is a diagrammatic view of sta ,tiigp-Abf this signal. system. i '-"Fig.' 2 is a siniilar view of station B. Fig. 3.:iB a similar view of station G p Fig, 4 is a ggggrammatic representationof a grade crossing in the system, and

be sufficient to cover the others, and-such in struments are operated by power supplied to the track from two independent blocks, whlch blocks are arranged one on each side Patented July 3, 1917.

of the respective station, as for instance,

blocks A and A at station A; blocks B and B at station B; blocks C and C, at station I and blocks D and D at station D.

Like instruments and. equipmentv in each block, as aboveTset-forth, are designated by the same reference characters, and the blocks are separated by the induction bonds 1., such for instance as between block A and block B, and the other inductionbon'dcQ, located at or near the siding A", as indicated at station A.

By referring to station C, the power for controlling-the signaling along the rails/tand 5, in block C, is supplied to the track at the induction bond l'by Wires 102 and 103 from transformer 3, which takes the current'from. the line, at for instance 2200 volts, 0131 591118 high potential, and transforms the circuit-Which feeds tl'irou h wires 102 and 103, into the rails 4 and 5, eading to the opposite end of the block at station-C, Where it flows by wires 104 and 105 to the track relay 6, having one of its coils 6', energized by a se arate transformer 7, through Wires 106 an, 107, atllO volts.

' current to 1 0 or llvolts, for the signal track The various circuitsand.instruments con.

trolled by this relay '6, 0t block 0, are as follows, viz :-the circuitbreaker 8, located at the siding (lflofstation C, the line relay 9,.through the repeating relay 25, in the ad 'jacent block B", the circl lit breaker 10 in block Cfi and with. .wfiditiiens favorable to station C, the light slgnal'ind cators .12 and controlling circuit breaker 11 at 13 .also'being operated.

.wire 1.1.7, wire 106 to the tmns't'ornv wire 11S, armature 15*, ioint 15*, wire-1e, signal indicator 14, wire 1 wire 100 and The circuit closed to control the circuit breaker S, through armature 6", point 6", wire 1.08, circuit breaker 8, wire 18, Wire 109, wire 107, trang-sforrru-r 7, wire 1 06, wire (5 to armature 6*.

The circuit closed to control the repeating relay 25, is from transformer 7, Wire 106, Wire 6", Wire 6, armature 6, point 6, wire 25, repeating relay Wire "25, Wire 112, wire 111, wire 107 to the other side of the transformer. The energizing circuit for the line relay 9 is from the secondary of transformer 7 of station D, wire 1 wire 6*, armature Gflpoint 6, wire 9", reiay 9 of station C, wire 9', wires 107' and. 11.3. to the'transformer 7 at station D.

The circuit breaker 10 shown in Fig. l is controlled through transformer 7 of station C, wire 107, Wire 109, Wire 10* of Fig. a, circuit breaker 10, wire 1.0, point 1.0" of relay 9 at station (3, armature 9, wire 10', Wire 25", point 6, armature 6", wire 6, wire 106 to the transformer 7.

The circuit breaker 1.1, operated by a circuit as follows tran:= wire 107,

ormer i wire 109, Wire 11, circuit hrealier 11, wire 17', ar iature 9, point 2%, wire 115, point armature 15, wire 116, Wire 106 to the transformer 7,

The lightsignal indicator 12, is supplied with current from the transformer 7, throilgh wire 107, Wire 1019, Wire 1:3, light signal indicator 12, wire 12", point 6, armature 6 Wire 1.1.6, point 16% armatqj 1 The light signal indicator 13, is iar ipliiitl with current from the transformer 7, through Wire 107, wire 109, wire 13, light signal indicator 13, Wire 1.3", JfCYL se point 6, armature 6- Wire 6*, wire 100 to the transformer 7.

Referring to the line rei the instruments controll station. E, are as 0110 circuit i 10 and .11, and light signal indicator 14f. The circuits formed to operate the circuit breakers 1.1. and 10, are identical with those just described as pertaining to station 0, but in this instance the light signal indicator 14;, is operated from the transformer 7, Wire 106, conductor 117, armature 9*, point 0" wire 107 to the transformer 7.

.l'n lilo-cl; C it will be seen that the track. railed: and 5, are electrified hy the trans former 3 of Fig. through u 'ires- 1 18 and 11.9, and control the track relay- 15. r irongh wires 120' and 1'21 in said hiocl" nis relay 1.5 in turn controlling}; the 1' l6 1G iirblocii I circuit 1.7 in block C, circuit breaker 18 at the siding Cf, and. opening one side, of the double ci *cuitsup-- plying current to controi'the ci-rc breaker '11 at station (I, the light signal in icator 14- in block C and light signal indicator 19 in block 0, being operated simultaneously with. the above instruments.

The line relay 16 of the block T), is 511')- plied-with current from thetransformer through wire 107, wire 16', relay 16, wire 122, point 15", armature 15, of the relay 15 at station C, Wire 11.6,.Wire 1.14., coil 15*, wire .107, Wire 9', relay 9, wire 5), point 6", station I), armature 6, Wire 6', and wire 106 to the trzu'isfifiriner 7 'i he circuit breaker 17 in the bloc-i: C, is sapg iliel with current from the transformer 7, at s: ation C, throu h the wire 1.07, Wire 1.0!), ,-ircuit breaker. .1, wire 17, point 6, armature 6', wire. 1.23, point 15*, armature 15", wire 116, and wire 100 to the transformer 7.

The circuit breaker 18, at the siding C is ansiormer 7, 18''. 110, cir- 19", point 15, armature 15", wire .116, and

o-zize 1.06 to the transformer 7.

.lihe line relay 16 of block D", controls the circuit breaker 11, at station .1), the circuit breaker-l7 in block I), and the light signal i'i licator of block I), all oi which have described in operative relation in station G.

The loop circuit, comprising wires 10 and 1.0 and armature 10 and which is connectcil. around the insulated joint 20 of liiocik C of sufi'icient carrying capacity to eupgily current to operate nmchauiem on the train or car, a sulatml joint is located (1 oily opposite the insulated joints 20, in the other raii. The two ins ted joints 20 form a combination, which under proper conditions, breaks a local circuit in a train passing ov 1' said. joints,

and this point 20, is designated as a .control-.

ling or Stopping point in block it iyill he-see-r in t there are two other i.nsulatcil joints and mounted in. the mike, one a suliicient 4 tance away to pen wit a single track of :1 ha eulateil section, n-'5. the other joint located a rail length from the signaling p()l!i!3, Wh1lG around. these insuiateil joints are instelied mou-ind1mtive bonds 200 and 301., of suflicient carryingcapacity to transmit the 'en-'. Lire return circuit of :.':e propulsion or traf tic current travi-irsing the rails.

the above arrangement, it will be seen that the only possilnhty of obtaining a compiete metallic circuit between the insulated r to stand in the inso :markers 13 rail section andthe main rails of the, track, isby means of the loop circuit under control of the circuit breaker 10, therefore control loop circuits around the insu ated joints formmg train eontrol ,.mt$,'el1 d' w th filfilll v breaker 17 through wires 17' end 17 an the stoppingpo n themeae above set to c armature 17 controlli y 21; the circlllt bmakflr l8 throughthe wlres 1sand 187 and a tmels eontrollingthe' ar 229' thewimult breaker, s. th ou its wires 5' and 8" snd'nrmat le 8 con Hing theetoppv some the 2o circuitbreolrerfllnthroug citsyimgl'l end mll'mlhlrell-P mhtmlhngthe I fii i' 'otoememcx. l. it I h l. "r bqi epormetheod mat ll Woiithem indwtire.

Kmotflw mammogram-1 am- 0 signal indicator i sread truck; as designet d y T he c directi or ii which thecar ob ain-1 trayeling, and be v id mm mi ht c m cato e, th are" harm-stem mo l mu new -sidthe rmkyoou mmwg nd catsthe conditioner e h ,l 21 L o erheate e f j ,1 z detenoemlthelpoint btthesw ltchm or tin-1 56 how one th m e wer ld w t v Th m rk r ght not d .7

PIMWK thmfunctmn o v c 1 y Inv thisunanner it will obvious that a in block; B opens the circuit l breaker 30, contro1ling aniepproeching oer 'j two, lighting aipo nt use :2 T

by the track relay, 6, in block Cfas before described, and controls circuit breaker 27, by the following circuit, transformer 26, wires26' and, armature. 25", wire 2'1", circuit breaker27 and wires; 27' and 112 back to transformer 26. Circuit breaker 27 controls the 'signali ng point 28 by the wires 27 and 27" and armature 27 and also the extra line role 29 in'block C is controlled by the truck ay lfiinblock B, asfollows: from transformer 7 at station B, along wires 106 and l16;,srmature,15v, ppinty15", wire 29'and'wire 29" of Fig. 3, relay 2!), wires 29", 112 "and 111 back to transformer 7 art-station B. t h c y B0" This secondary relay 29 controls another circuit supplied from the transformer 26, he folltpwsy-Mmsture 29,ipoint 29?, in30:v Cireujtbreekerfil), wires 30" and112,-trans- 1W26and W1vl'eS26" andv123, thus su plying EQWN fonholdin thesolenoid'oft e ioiiouit reakerBQcl tocontrol-thesig m1 9 1M13 hmu'ghath wires 30, an 3.0" end) immature 30, aseboye described.

Thelocal circuit brwkersnoontrolled b so theirelays 25wend 29,11,150 act as repeeters to trensrnit theysignalson ;;to the" H erline mysslocatedcat-the sidings Ias l ne relays 9- at stetion B; and the line relay 16st ste- (3, the, arme'tures 25'? end" 291", acooml6 n bloek Gfyopens, the circuit breekera 27 in Bflzthus controllingwtheapproaching our in: the oppositerdirectlony As these neliniggmm s23 e d 31 arellocfl'ted t in a, curve, thecers will elwaysbe protected against accidents v Another condition stick? 1 in} single. track a systems, is illustrated in 'i n", and itnis assumed for -.insta-nce' that this shown: ,forth :conditions preyai at ljeeehstation nnd block, eloug therightuf condrtibnbe a gradeof asteam mama, Inthis: oese, the steam; railroad rails 32, are bonded for at, leastone-helf mile in each direction frorn the crossingor 1'15 intersection of'the two railroads with insulate'd, OiIItSII', located in the traclr, as shown; and l with this'is employed a. "direct current from gravity betteriesz33 1.11635, locatedhat ail distant point/on said steamfirailroadx A 120 relay 34 sIconnect'ed 1: with; the battery 33 upon one side vof the ucrossin whilekthe 'relay 36 withbattery 35 is :on t e other side 30f thecrossing; The carmatures of these two relays 34= and 86, control local .circuits gffeddzb from local trsnsformjer 37 through wires 37' and; 37, said transformer "goyerningthe operation of thec-ircuit breeker 38, having control of the signal point 39, and the ci'rcuit breaker 40, having control of the signal 130 in block Q, and-inn similhr manner, mean reltin ,jdistance; that. isye'pproxir 106i inatelylOOO eet tromthmdangerous:point I grem. 11in block 110 i point 41, each approximately one thousand feet, or more, from the danger point of the crossing, thus insuring absolute protection against an approaching train on the steam railroad.

When the relay 34 is energized, the annature 34, contacts point i-Afi'and the circuit breaker 38 is energized through the transformer 37, wire 37",armature 34',

wire 38, circuit breaker 38, wire 3 point 36, armature 36" and wire 37'; The armature 36 is operated by relay 36, and forms x suppliedfrom transformer 3, to rails Land '5, in block B is shunted by the car wheels, thus deenergizing track relay 15 of block a circuit through the transformer 37, wire 37, armature 36', point 36", wire 40", circuit breaker 40, wire 40 and wire 37". The circuit breakers 38 and 40 have their usual wires 38 and 38", and 40, and i0", respectively, and .armatures 38" and 40.

Having described the operation'and circuits, with the instruments anditheir function, the'traflic conditions, which might' arise on a high speed electric interurban railroad, which it is desired to protect with this system, will be given in detail.

Assuming that a car is located in block B, just leaving stationB, and running in the direction of station 0, having passed over theinduction bond located at the signaling point 24. This car has all signals and sto ping points clear in the direction in whic it is going, as far as the induction bond, located half-way between stations B and C, at the dangerous point of the curve. It will be evident that that signal current 3, and this action has set the danger circuit breaker'lT, which will stop any car approaching from the direction of the stop- )ing point'Ql of block B". The circuit eaker Scout-rolling the oint 23 at the siding has also been opene and will prevent any car that has already taken the siding from leaving or going on themain track, until after the moving car which controls this circuit breaker has passed out of the danger zone. Simultaneously with this, the light signal indicator 14 will show red, while the marker, indicator 19 for the circuit breaker 17 will also show red. In advance ,of the train or car, it will be seen that on' -'the opposite side of the dangerous curve,

and at a full braking distance from the pointof danger. a line relay 2!), has been 'tion; and the line'rela opened, deiinergizing the circuit breaker 30. thus placing point 551 in a condition to stop carapproachingfrom that direm '25) has repeated its signal to line relay 16 at'station C; of block C', and in turn deiinergizes the circuit breaker 17 of block C, thus stopping point 21in block 0', open to control snappy-caching car. Simultaneouslythrowing the oint 34:,

, point 3-1", armature 34 with this, the signal indicator 12 of block C, indicates .red and yellow,'the green or clear signal having been cut out. By this means, -the moving car is protected from any possibility of a car getting into thesame block without being halted at one of the signaling points, even though the motorman disiegarded the light signal given by the light signal indicator. As the car approaches. station C, where it passes over the induction bond 1 between blocks B- and C, the signal and controlling instruments change to the following conditions, viz.,- I

track relay 15 in block B, again becomes energized, and all the instruments under its control assume their normal position, while the track relay 6, in block C, has been shunted by the car wheels, and in turn controls another set of instruments and opens-thev track clear for the distance of another block in advance of'the moving car.

'Th track relay 6, controls the line relays 25 and 9, in block B, and in turn the circuit breakers 27 and 10 in the same block, thus controlling the stop ing points 28 and 20, respectively,'while t e signal indicator 14 of block B, shows red and yellow. In

advance of the car, the track relay 6, opens the circuit hreaker 8 at stopping point 23 on the siding, thus preventing any car that might be standing there from running out on to the main line, which might cause either a head on collision, or what is termed -s.

sideswipe collision to the approaching car. i When the moving car passed from block B? into block C, a circuit breaker 17 in block C became energized, and simultane- Y.

ously with that movement, a circuit breaker 10 in block C"became dei-Tnergized, thus controlling thestopping point 20 of block (3 approximately one thousand feet from the:

siding, while the signaling indicator 13-of station 0', showing the condition of the.

stopping point 20, is now red, thus insuring protection from collision with an approachmg car to the car moving in bloc ward station C, with everything clear in its 'adv'ancepast or beyond the induction bond 2, located at the siding of station (1.

, Assuming that a car leaves station D, ap-

just entering the block D, and having passed the induction bond 2 at station D, thetrack relay 6, ofblock D, Whichis fed fr m transformer 3,

shunting the current across the rails 4 and 5, of-the block D. becomes'denergized it immediately opens the armature control i 8-,at station Dsiding; t e circuit breaker 10" in block DE; line rell .y'9 in bl ck in throws the signal indicator 12 in station I) to red, and

the maker indi atoji 13 C, we I fproaching in the direction of station C, and i 12a between block C andfblock, D; "and 1S deenerg1zed,duetothe axles of thecar When the trackrelay s r thecircuit break r i,

- in station D also to red. The line relay 9, at station O, in the bloekG has been opened and has controlled the circuit breaker 11 station C, which has one side of its controlling circuit opened, by the car approaching in block J, but has the, other and only remaining source of supply opened at line .rclay l) of block C, and thus cut ofi the last S1; are of supply from said circuit breaker w ill, therefore de'nergizing it and opening circuit at stopping the train controlling h b wk T e circuit r or point 24 at station (J.

I also controlled by the line relay 9, it.

having already been opened by the track re la 6, by the'car in block C. The signal ind. itorj 14 of block G now shows red and v, "while the green is cut out. The actual condition of the signals. and train control points at stationG, dueto the location 1c two cars, one 1n; block O, approaching ion (.3, and the other car in-block 1), ap-

n achin station (3 ,causes the train control 1 a points and 24 to be open, so that they will stop any. car crossing same. The circuit breaker 8 has become deenergiaed, opening the car controlling point 23, which thus pre- 'vents any car leavlngthe siding; the signal indicator 12 shows red or a home signal; the marker signal 13 also shows red, While the 39 signal indicator 14 shows red and yellow for-distant signal. 7

In this way, a car'in block C, will be stopped when it reaches the train control point 24:, the signal'indicator 14; having also -1ndieatcd that there is a car in-the distant block; between stations 0 and D, inblock D, shown. by the red and yellow light. The marker 13 located at the siding that the train control 20 has opened will also indicate the 40 locationof the approaching car, and sets. etc for gither. The. car therefore at the siding will enter the same, and await the arrival of the approaching car, the car in the siding being held, for it will be impossible for it to leave without being stopped at least several times.

Assuming that the car takes the siding at station (:1, this action innnediately clears up the train control points 24 and 23, and the signal indicator 12 goesto green. It has also cleared all the train control points in station 13, and throws the signals there to green or clear.

' Should the car in block I) approaching :f'thim U, cross the induction bond 1 into hlo f (3 the train control points actuated by circuit breakers 8 and 10 of station I) will be clear, sin]altane'ously deiinergizing the train (K'JlllJFOl point 21 in block I), cutting to out one source of supply of the train control yninnt ill. The signals at station D will then sl' w in 12 red .and yellow, and lllitl'lfiill i out out.

- ln station (,3, the track relay 15 of block (.1 becomes decnergized, thus changing the preventing the car that has just entered the b siding from again'entering the main line until after the point has been cleared. The a signal indicator '14 has changed from yellow and red to red, and the markerll) indicates red," thus leaving-a clear track for the car approaching station G, through block .C, until after the car passes the siding at the induction bond.2. At the same time, this car is protected against any car approaching by'the train control point 21, or from a. B0 side-swipe or head-on collision, due to the. car standing in the siding. by the stopping point 21 in block D. l

Should the ear pass station C, from block U in the direction ofC', and enter block C, 35 across the insulated joints and induction bond 2, the car controlling point 21 clears in advance of'the approaching car, while the stopping, point 20 is immediately set, and the controlling points at the sidingC are shifted, thus closing oints 22 and o ening v 23. In this manner, t e car onthe si ing is released to leavethe siding toward block C but not in theidirection of block 0, while the signal markerlB showsthe condition of stopping point 20 toth'e car standing on the siding, as Khe red Ii'ghtis exhibited,- and the signal 14 'mmediately passes to green or clear, simultaneously withthe signal indicator l2 exhibiting red. Thetrack is now chair for passage from block C to block B,

of station B, and at the same time, thisis protected against acar leaving the siding by stopping point 23, as well as an approaching car from the rear at stopping point 20, While 5 at station B,-the circuit breakers at the stopping points and the signalshave been actuated as explained with reference to station C. The stopping point 22 has cleared in advance of the car standing on the siding C, 1 thus permitting thefcar to leave the siding in the direction of the" station D; and as soon the car that passed leaves block C, and passes. over the :insulated ]'oints at the induction bond 1 between blocks B and C, the

Jteri ng another car. a a

If the car which first approached station C instead of entering the siding remained upon the main line in block (Y, the signal lights would indicate plainly whorl: the car was located, that is app'rmtchingthesiding from the opposite direction, and if, the mo-- torinan observed the light signals, he need 'notbe automatically stopped, but if on the contrary he failed to observe the signals, the car is automatically stopped, and held there ziplon the main track, at or near the ,lsidliln is o ns the 'stopping point 20 w 1s locatedgdt braking distance from the siding, sdthatthe approaching car will itself, be

- automatically stopped between stopping points 24 and 20, thus protecting both cars from head-on or rear end collisions. I,

In case, one of two approaching cars mov ing toward the switch at station C,lshonld pass overthe stopping point 21 while the other passes from block ,D to block CF,

' crossing the insulated joints at the induction bond 1, thefcar in block C, would not receive the signal at stopping point 21 in time to stop, but the circuit breaker 11 at station .C, being controlled by both cars, is deenergized, thus openingthe stopping point-24 at station C, to stop'the car in block C; and it in turn controls stopping point 20 in block C to stop acar'coming froin that direction,

thus protecting. both cars, even though they maybe approaching at high speed, they hav} ing a in {braking distance in which to be stopped automatically. I Atfl station B, there 'is located what is termed an open ended switch, Where in such cases the ClIC-llltbreaker 8, -will be controlled by'the track relays ofboth'blocks, namely blocks B and BF; In this way, a car approaching the siding from either direction will hold any car that has taken the siding against leaving, and thus prevent an accident. The car is held in theswitch until the approaching car has passed into the adjacent block. In this instance, it will be noted that the induction bond 2, which separates blocks B and B is moved about one cars length fromthe point ofthe'switch, thus enabling a car to approach and take a siding without being endangered by an approaching car. I, e

In other words, assuming theta Tar approabhes station B, from station A through block B, it will be held at car controlling points 20 and 23 in the stopping position, which will avoid any dangerfrorn an approaching car'or from a car! in the siding; and at the same time, in case a car is approaching from the opposite direction, it will hold the carnear the siding in check, and avoid an accident from that direction.

There is another tra-flic condition thatmay arise, where two. cars approaching each other leave station B and station 0, simultaneously, and cross the insulatedsection'at the induction bonds 2, in each block. It might be possible with this system for them not to sto one another at the stopping points 24 0 each block, butthey still" are secure and safe, for the reason that the car in block Bfl in crossing section 24, W the 81" and thereby avoid the possibility of an accident.

\Vhcrever there adangerous curve along the right ofway, it is protected as illustrated by the repeatingsignals on each side vof the danger point, as indicated by line relays 25 and 29, con.trolling the stopping points 28 and '31, as. previously described, thus avoiding collision in these places. Grade crossings are protected in a similar manner by wiring the track of the crossing railroad in such a manner that it will protect and'control any approaching car on the electric railroad. This is fully illustrated in block C.

By tracing out the various circuits, it is shown that one. car can readily determine from the signals when approaching the siding, the exact location of any car within two blocks ofv said siding, thiis' informing each motorman, of the exact condition of the track in front and in the rear, and also I at a high rate of speed, the insulated joint 1 having been crossed, between .blocks B and C, and also between blocks C and D, both moving toward station C, it willbe seen that the car in block C, throws controlling point 20" into stopping. position, and the car in blocks C throws controlling points 2-]. open, and both then hold stopping point 24 open. In this manner both cars will be automatically stopped as they pass over controlling points 20 and 21, and

will-therefore be brought to a standstill before they reach station C, at a siding, which will enable them to pass safely.

From the foregoing description of the diagram and the operation of this safety signal system, it is evident that its greatest valueis in haviiig thetrack circuits so wired and connected by means of the insulated rail sections, which are either looped around 'by inductive or non-inductive bonds, and

placed under the control of a circuit breaker, which" is operated by a distant si and equip 'with'the instruments for reeeivi said indicationsfis set forthin a 'plication Serial No. 555,804, the ear or tram will not only.

the mgnal' in the cab thereof. II

at all times under anal. cir- I 'cuit, so that when-a car is proper y wired" tomatic control, due to the arrangement or disp ltifil! oil the track signal circuit, and yet is able at the same time to give signals in the usnal'form. By this invention ahsolute prote..:tion is assured, even Where the signals have been disregarded, either by carelessness or the inability of the operator to (.OIltI'Ol his car 01' min.

What is claimed, is

A railway signal system comprising track divided into blocks, a circuit for each block, train controlling means in said track, a.nd 1uea!1s controlled jointly by the two bloc 'khireuits on opposite sides of said train controlling means to control the operation of said train controlling means.

A railway signal system comprising: a track divided into blocks, a circnit. for each blcx 1 an insulated train controlling section in said track, a connection Between the insulated section and the track outside the section, and means controlled by the consyw current disturbance of two block circuits on opposite sides of said train controlling section to control, the connection between said section and the track outside the section.

3. A railway signal system comprising: a

main track divided into blocks, a circuit for each block, a branch track. connected to said main track within one of smd'blocks, R

train controlling means in said main track between the point of connection of said 'hranch. track with said main track and an controlled adjoining block, and means jointly by the circuits of said. adjoining blocks 'to control said train controlling means.

, In testimon that I claim the foregoing my own, lTl-have hereto afiixed my signature in the presence of two witnesses.

, GUY P. THURBER. Vitnesses:

JOHN F. Swinnr, PAUL ALANn. I t 

